The present invention relates to apparatus for processing tobacco leaf and in particular to a system and apparatus for grading and sorting such leaf which provides improved means for feeding the tobacco thereto and for receiving the same for grading.
Until recently the only way of grading and sorting tobacco leaves (i.e. separating the desirably colored and formed leaf from a mass of leaves supplied by the farmer) had been by hand. That is, manual laborers were required to pick through the collected leaves and extract from amongst the predominantly good leaves, those which are of the wrong color, texture and/or degree of uniformity required for the product. The picker was also required to extract the suckers, stems, rope, and any foreign matter collected within the leaf. Recently, automatic methods have been suggested to replace this total hand operation. In U.S. Pat. No. 3,368,568, one such method was suggested wherein the leaves were tumbled on a rotating turntable so that the leaves became separated and under centrifugal action were forced to arrange themselves individually for passage before a photo electric detector which would sense individual leaf of improper color, shape and uniformity etc. An air injection system was provided to remove the thus sensed improper leaf. Subsequently, in U.S. Pat. No. 3,380,460, Apr. 30, 1968, of F. Fuis, Jr., a linear table was employed dropping leaves through a number of gates. The first system has a disadvantage in that a large turntable was required to provide sufficient room for adequate separation while the second system had the disadvantage of having a complicated complex table and gate arrangement. Separation itself was not uniform and the speed of operation in both systems, was insufficient so that the total throughput did not match either in time or total cost that produced by manual labor.
More recently, apparatus has been disclosed in U.S. Pat. No. 3,750,882, issued to Gordon W. Hays, wherein the rotary turntable was replaced by the conventional linear "picking" table on which an endless belt conveyor was arranged. Such tables are common in every leaf processing plant. Here, however, the electronic and photo-detection system required that the tobacco be fed to the moving belt at such a rate that the tobacco became arranged on the belt in a plurality of parallel longitudinal rows or streams in each of which piece of tobacco had to be separated by a given distance from its preceding and succeeding piece. Single file rows of tobacco leaf spaced apart approximately 12 to 24 inches was required to enable efficient detection. To accomplish this, a complex mechanism for proportioning, dividing, separating and arranging the leaf in predefined channels was provided wherein the single file arrangement could be obtained.
To the contrary, it has now been found that the arrangement of leaf, either on end, up against a centrifugal wall or in predefined rows is not necessary. We have found that tobacco leaves need not be arranged in absolute single file, and that higher speeds for photo-detector scanning, movement of the belt and overall operation could be obtained without the complex mechanism suggested by the aforementioned prior devices.
Other disadvantages of the prior devices lie in the means for receiving the tobacco once it is selected and pneumatically ejected. In particular, the hoppers for receiving the leaves are subject to drafts and wind interference which affects the trajectory of individual leaf. Also the separation between adjacent hoppers has contributed to various operational malfunctions and hang-up of leaves on the edges of the hoppers.
It is an object of this invention to overcome the defects of the prior art.
It is another object of the present invention to provide means for feeding tobacco to a moving conveyor freely separated from each other.
It is another object of the present invention to provide means for feeding tobacco leaves to a scanning photo-detector wherein substantially each leaf is capable of being individually scanned.
It is an object of the present invention to provide a system of the type described including means for increasing the speed of the conveying table and the transport of tobacco leaves to the sensing head at faster intervals.
It is a further object of the present invention to provide an improved tobacco leaf grader and sorter operating at advanced high speeds, yet simpler in structure and operation.
Additional objects and numerous advantages will be seen from the following disclosure.